In the processing of carrier substrates for electronic circuits, such as printed-circuit boards or ceramic substrates, the carrier substrates are aligned in the individual processing stations with respect to a predetermined position. To affix, for example, printed circuit traces or components to the carrier substrates at the positions intended for this, the carrier substrates are mechanically aligned in the fixture of a screen-printing station for imprinting circuit traces or in the fixture of an inserter (automatic component-insertion machine) for affixing electrical and/or electronic components. To this end, it is generally known to use devices for aligning a carrier substrate, which have several centering elements which engage on the peripheral surface of the carrier substrate, shifting the carrier substrate into the desired processing position. The centering elements can be adjusted in the device relative to the carrier substrate by an adjusting device and can be made to engage on the peripheral area of the carrier substrate in a spring-biased manner. By pressing the centering elements against the peripheral surface of the carrier substrate using elastic tensional force, the carrier substrates, whose size varies within a certain range of tolerance, are prevented from being damaged already at the time of engagement of the centering elements.
It must be regarded as disadvantageous in these known devices that when working with relatively brittle carrier substrates, such as ceramic multilayer substrates and, in particular, LTCC substrates, the substrate edges often break off in a muscle-shell shape at places where the centering elements engage, and that sometimes the carrier substrates break into pieces. This is due to the fact that the friction between the stop faces of the centering elements and the peripheral surface of the carrier substrate is quite substantial, and that the centering elements are not movable along the peripheral surface of the carrier substrate, but are only able to be moved towards and away from the peripheral surface. Therefore, a jamming of the carrier substrate between the centering elements cannot be ruled out. As a result, during processing, a short jerky movement produced, for example, by negative pressure applied to the bottom side of the carrier substrate or by the compressive force of an SMD inserter (component-insertion machine) can lead to breakage of the brittle carrier substrate. A further disadvantage is that the rubbing of the carrier substrate at the stop faces of the centering elements leads to premature wear and tear of the centering elements, which can result, in turn, in an imprecise alignment of the carrier substrates, as well as in break edges at the peripheral surface of the carrier substrates.